• Title/Summary/Keyword: S-curve profile

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Model-Based Simulation Analysis of Wicking Behavior in Hygroscopic Cotton Fabric

  • Hong, Cheol-Jae;Kim, Byung-Jick
    • Journal of Fashion Business
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    • v.20 no.6
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    • pp.66-78
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    • 2016
  • Hygroscopic knitted cotton fabric was found to spontaneously absorb water showing a significantly wide concentration gradient in the absorption direction. A semi-empirical diffusion model was introduced to describe how the wicking behavior compared to the classical capillary model (Washburn's equation), which has been widely used in the textiles industry. The capillary sorption curve and the permeability coefficient, which are key variables for the model equations, were measured using an electronic balance. The concentration profile as a function of the wicking distance and the elapsed time was derived, based on the diffusion model. From the concentration profile, the wicking distance detectable by the human eye or a digital camera with the aid of an image-analysis system, could be described realistically as a function of the time. The classical capillary model could be modified by introducing the tortuous correction factor to match the diffusion model. Wicking models and data-processing techniques in the work could provide useful tools for objectively evaluating the textile's wicking performances.

Fatigue Characteristics of SM490A Welded Joints for Bogie Frame (대차 프레임용 SM490A 용접재의 피로 특성 평가)

  • Park Jae Sil;Seok Chang Sung;Koo Jae Mean;Shin Jae Ho;Goo Byeong Choon
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.12
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    • pp.146-153
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    • 2004
  • We compared the fatigue characteristics of weld metal with those of base metal, and not heat-treated with heat-treated. Also, we examined the influence of bead in a viewpoint of fatigue life. From the experimental results, it has been seen that the fatigue characteristics of welded specimens grinded the toe of bead are slightly better than not grinded. We have seen that the fatigue life is affected more by the stress concentration on the profile change in the weld toe rather than by residual stress influence, because heat-treated or not had almost no influence on the fatigue characteristics.

A Study on Epitrochoidal Tooth Profile in A Two Teeth Difference Cycloidal Reducer (2치수차 사이클로이드 감속기의 형상설계에 관한 연구)

  • Shin J.H.;Kwon S.M.;Kim B.J.;Kim J.C.;Kim M.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.389-390
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    • 2006
  • The cycloidal reducer is one of the velocity controlling equipments in machinery. It has advantages of the higher reduction ratio, the higher accuracy, the easier adjustment of the transmission ratio and the smaller workspace than any other kinds of the reducers. This paper proposes a simple and exact approach for the lobe profile design of the two teeth difference cycloidal plate gear, which is different from the standard cycloidal reducer, by means of the principle of the instant velocity center in the general contact mechanism and the homogeneous coordinate transformation.

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Evaluation for Fatigue Resistance of Small Wind Turbine Composite Blade according to GL Guideline (GL Guideline에 의거한 소형 풍력발전용 복합재 블레이드의 피로 저항성 평가)

  • Jang, Yun Jung;Kang, Ki Weon
    • The KSFM Journal of Fluid Machinery
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    • v.16 no.4
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    • pp.15-21
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    • 2013
  • This study aims to estimate the fatigue resistance of small wind composite blade using the fatigue life estimation formula in the GL guideline. For this, firstly, we estimated a turbine blade's bending moment spectrum by using wind profile wind profile and BEMT. And fatigue tests were performed to obtain the S-N curve of composite materials used in blade. In addition, a finite element analysis was used to identify fatigue critical locations and fatigue stress spectrum. And the fatigue resistance of composite blade were evaluated using the rainflow cycle counting, and Goodman diagram and the fatigue life estimation formula in the GL guideline.

Utility of False Profile View for Screening of Ischiofemoral Impingement

  • Kwak, Dae-Kyung;Yang, Ick-Hwan;Kim, Sungjun;Lee, Sang-Chul;Park, Kwan-Kyu;Lee, Woo-Suk
    • Hip & pelvis
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    • v.30 no.4
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    • pp.219-225
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    • 2018
  • Purpose: Ischiofemoral impingement (IFI)-primarily diagnosed by magnetic resonance imaging (MRI)-is an easily overlooked disease due to its low incidence. The purpose of this study was to evaluate the usefulness of false profile view as a screening test for IFI. Materials and Methods: Fifty-eight patients diagnosed with IFI between June 2013 and July 2017 were enrolled in this retrospective study. A control group (n=58) with matching propensity scores (age, gender, and body mass index) were also included. Ischiofemoral space (IFS) was measured as the shortest distance between the lateral cortex of the ischium and the medial cortex of lesser trochanter in weight bearing hip anteroposterior (AP) view and false profile view. MRI was used to measure IFS and quadratus femoris space (QFS). The receiver operating characteristics (ROC), area under the ROC curve (AUC) and cutoff point of the IFS were measured by false profile images, and the correlation between the IFS and QFS was analyzed using the MRI scans. Results: In the false profile view and hip AP view, patients with IFI had significantly decreased IFS (P<0.01). In the false profile view, ROC AUC (0.967) was higher than in the hip AP view (0.841). Cutoff value for differential diagnosis of IFI in the false profile view was 10.3 mm (sensitivity, 88.2%; specificity, 88.4%). IFS correlated with IFS (r=0.744) QFS (0.740) in MRI and IFS (0.621) in hip AP view (P<0.01). Conclusion: IFS on false profile view can be used as a screening tool for potential IFI.

A STUDY ON THE FACIAL ESTHETIC PREFERENCES AMONG KOREAN YOUTHS: ASSESSMENT OF PROFILE PREFERENCES (한국 젊은이의 안면미 선호경향에 관한 연구 : 얼굴의 측모평가를 중심으로)

  • Song, Sejin;Choi, Ik-chan
    • The korean journal of orthodontics
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    • v.22 no.4 s.39
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    • pp.881-920
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    • 1992
  • This study was designed to assess profile preferences among Korean youths in the year 1992. Facial esthetics was evaluated by means of silhouette profiles, eliminating the influence of a number of aspects that may affect judgment when normal lateral photographs are used. The main points of preference to be clarified here are as follows. First, on facial convexity, Second, on nasion depth, Third, on mentolabial sulcus depth, Fourth, on the position of upper and lower lips, Fifth, on facial type according to Angle's classification of malocclusion, Sixth, on Song's tangents. The 54 subjects printed in questionnaire as black and white silhouettes were selected from 300 tracings from cephalometric radiographs of people whose age ranging from 11 to 20 years. Photographs of six female subjects were retouched by computer graphic software and printed in color and black/white photographs which were used for adaptation of eyes of participants in selecting profiles in silhouette. They constitute 2 questions. The 54 subjects were grouped as 22 questions, each of them composed of 6 subjects, according to the aspects to be clarified. Twenty four questions in total were asked to assess profile preferences. For the assessment, the profile line, the facial esthetic triangle, Song's tangents, and Angle's classification of malocclusion were introduced. The profile line is composed of 11 component points which are Trichion, Glabella, Nasion, Pronasale, Subnasale, Labrale superius, Stomion, Labrale inferius, Supramentale, Pogonion, and Gnathion. The facial esthetic triangle is composed of 3 tangents: A-tangent which is the tangent of dorsum of nose, B-tangent which is the line passing through Sn and Ls, and C-tangent which is drawn on the turning point of the curve which lies between mentolabial sulcus (Sm) and pogonion (Pg). Angle's classification has 3 types of malocclusion which are Class I, Class II, and Class III. Class II malocclusion is subdivided into Division 1 and Division 2. The participants of the survey were composed of 861 college students (448 male students, 413 female students) whose majors grouped as Fine Arts. Liberal Arts, and Natural Sciences, and whose mean age 21.8 years. The statistics program SPSS/PC + of SPSS Inc. was used to analyze answers of participants. Crosstabulation, Chi-square test, and Kendall test were done. The conclusions are as follows: First, Korean youths have a tendency to prefer the slightly convex face to the flat or concave face. Second, they prefer a moderately deep nasion. Third, they prefer a moderately deep mentolabial sulcus. Fourth, they prefer the position of lips which are near to Ricketts' E-line. The position of the upper lip which is slightly posterior to E-line is preferred. The upper lip which lies too far anterior or posterior to the lower lip is not perferred. Fifth, they prefer most, according to Angle's Classification of Malocclusion, Class I facial profile which has a slight inclination to Class II division 2. The order of preference is Class I, Class II division 2, Class III, and Class II division 1. Sixth, they prefer the type 2 and 3 of Song's tangents. The facial profile within which A-and B-tangent meet is preferred. The facial profile which has Cotangent that .meets with A-tangent slightly posterior to the crossing point of A-and B-tangent or that parallels with B-tangent is preferred.

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Fatigue Life Prediction of the Carrier of Slewing Reducer for Tower Crane (타워크레인용 선회감속기의 캐리어 피로 수명 예측)

  • Cho, Seung-Je;Park, Young-Jun;Han, Jeong-Woo;Lee, Geun-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.3
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    • pp.131-140
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    • 2015
  • The purpose of this study is to predict the fatigue life of a planet carrier of a slewing reducer for a tower crane. To predict the fatigue life of the carrier, the inertia endurance test was carried out, and then the input torque profile for the reducer was obtained. The load profile acting on the planet pins that assembled the carrier was calculated from the measured input torque profile using commercial gearbox analysis software. The stress profiles of the carrier weak points were analyzed from the calculated load profile and boundary conditions using commercial FE software, and the stress cycles were determined using the rainflow counting method. Finally, the fatigue life of the carrier was predicted using the equivalent stress range by considering the effect of mean stress, and an S-N curve was drawn up using the GL guideline and the cumulative damage law.

Optimal Die Design for Uniform Microstructure in Hot Extruded Product (열간압출품의 미세조직 균일화를 위한 최적 금형설계)

  • 이상곤;고대철;류경희;이선봉;김병민
    • Transactions of Materials Processing
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    • v.8 no.5
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    • pp.471-481
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    • 1999
  • The properties of deformed products are generally dependent upon the distribution of microstureture. It is, therefore, necessary to make the distribution of microstureture uniform in order to achieve the best balance of properties in the final product. This is often a demanding task, even for conventional materials. It is become essential to achieving mechanical integrity and a desired combination of microstructure and properties. The objective mechanical integrity and a desired combination of microsttucture and properties. The objective of this study is to design the optimal die profile which can yield more uniform microstructure in hot extruded product. The microstructure evolution, such as dynamic and static recrystallization as well as grain growth, is investigated using the program com-bined with yada and Senuma's empirical equations and rigid-thermoviscoplastic finite element method. The die profile of hot extrusion is represented by Bezier-curve to define all available profile. In order to obtain the optimal die profile which yields uniform microstructure in the product the FPS(Flexible Polyhedron Search) method is applied to the present study. To validate the result of present study the experimental hot extrusion is performed and the result is compared with that of simulation.

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A Study on the Reclamation Earthwork Calculation Formula (매립토공량 계산식에 관한 연구)

  • 이용희;문두열
    • Journal of Korean Port Research
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    • v.15 no.1
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    • pp.87-97
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    • 2001
  • The calculation of earthwork plays a major role in plan or design of many civil engineering projects, and thus it has become very important to advanced the accuracy of earthwork calculation. Current method used for estimating the volume of pit excavation assumes that the ground profile between the grid points is linear(trapezoidal rule), or nonlinear(simpson's formulas). In this paper the spot height method, least square method, and chamber formulas, Chen and Lin method are compared with the volumes of the pits in these examples. As a result of this study, algorithm of chen and Lin me쇙 by spline method should provide a better accuracy than the spot height method, least square method, chamber formulas. The Chen and Lin formulas can be used for estimating the excavation volume of a pit divide into a grid with unequal intervals. From the characteristics of the cubic spline polynomial, the modeling curve of the Chen and Lin method is smooth and matches the ground profile well. Generally speaking, the nonlinear profile formulas provide better accuracy than the linear profile formulas. The mathematical model mentioned make an offer maximum accuracy in estimating the volume of a pit excavation.

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Design of S-Shaped Path and Velocity Profile of Moving Stage Using Three Point Locations (3 점을 이용한 이동 무대의 S 곡선 경로 설계)

  • Jung, Kwang-Oh;Oh, Se-Kyu;Kim, Dong-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.1
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    • pp.67-76
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    • 2011
  • An exact curved path has to be fixed and velocity profile for travelling on the curved path is required by a moving stage. In this study, we decide the curved path on the basis of the information on three point locations. The path of the moving stage is traced by simulating the designed curve path and the velocity profile, and the results are compared with the given three points to determine how closely the moving stage follows the given path. Further, we propose a method to calibrate a curved path and velocity profile. The proposed moving paths were evaluated by performing experiments. Finally, the designed curved path and the actual path were compared.